Microphone.



C. W. UNDERWOOD.

MICROPHONE.

APPLICATION FILED MAY 27'. 1914.

Patented Apr. 20, 1915.

2 SHEBTS-SHBET 1.

c. w. UNDERWOOD.

MICROPHONE.

APPLICATION FILED MA'YZT, 1914.

1,1 Patented A r 20, 1915.

2 SHEEIS-SHEET 2.

l k. a?

Attorn eys 2 'view which will appear ments in microphones,

ing of the same and at ;.a

l CHARLES W. UNDERWOOD, 0F CROWLEY, WILLIAM M. EGAN, OF

LOUISIANA, ASSIGNOR 0F ONE-HALF T0 CROWLEY, LOUISIANA.

MICROPHONE.

Specification of Letters Patent.

Ratented Apr. 20, 1915.

Application filed May 27, 1914. 1 Serial No. 841,313.

To all whom it may concern Be it known that LLCHARLES W. UNDER- woon, a citizen of the United States, residing at Crowley, in the parish of Arcadia and State of Louisiana, have invented a new and useful .Microphone, of which the following is a specification.

The present invention relates to improveone object of .the invention, being the provision of a microphone,- in which the movable agitating members of non-conducting material which produce the necessary stirring and compression upon the minute particles thereof, are disposed in the form of a blade or strip longitudinally of suchparticles and are carried byor attached to the vibrating member thereof, that the most delicate sound vibration will be effective upon the particles and in which the frying effect is greatly minimized.

With the foregoing and other objects in as the description proceeds, the invention resides in the combination and arrangement of parts and in the details ofconstruction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed can be made with in the scope of what is-claimed without departing'from the spirit of the invention.

l nthe drawings-Figure 1 is a cross section through the base and one of the present microphones mounted as a differential microphone or telephone relay. Fig. 2 is a hor1- zontal cross sectional view through the easpoint above the poles of the electromagnets of two'watch" case receivers which are used in'connection' j with the present invention as a telephonerclay. Fig.3 is a top plan view of the casing for inclosing the differ- "ential microphone 1 when used as when constructed a relay. Fig. 4 is a top plan view of the microphone supports-Fig. 5 is abottoin plan view thereof: Fig. 6 is aplan viewof the diaphragm showing the blade or strip electrodes carried thereby. "Fig. 7 is an electrical diagram ofthe construction as illustrated in Figs. 1 and 2. Fig. 8 is a cross section through a telephone transmitter embodying the present invention. Fig.':,9 is aplan viewof the particle or carbon holder thereof. 'Fig. 10 is a 1 bottom plan view ofthe closure and electrode carrying member thereof.

Referring'to the draw ngs and more par- 'wi.th acoat conducting strips or blades 23, each-oneof particles during ber 5 of a Watch case receiver, said base have ingmounted therein, the usual permanent magnet 6, having the arms 7 to which are connected the pole pieces 8 of the two electromagnets 9.

lhe annular member 10 is screw threaded upon the casing 5 and maintains the diaphragm 12 by engaging the same at its periphery as at 11 relatively to the pole pieces 8, so that the same will be under the influence thereof. The annular member 10 is provided with the offset bridging portion 13, which is apertured as at 14, concentrically of the annular member 10 to adjustably receive the cylindrical stem 15 which is locked. in adjusted relation by means of the set screw 15 to thus hold the block 16 of insulation in proper relation to the diaphragm 12.

p This block 16, as clearly i lustrated' in Figs. '1 and 5, isprovided with two tangular receptacles or sockets l717,the.

parallel recphr'ztgm 1-2,

of insulatlon, are the two nonwhich is adapted to enter its respective;

socket 17 or 17' and thus contact the par;

:ticles 22 and be free for vertical, andothe'r oscillatory movements so as tofa'gitate-to produce the necessary compression of the the vibration of the dia phragm' 12.

Leading from the respective'metal plates 19 audit) is a conductorf2, while connected to the outer. plates-18 and 18 are con- (luctors 25 and 26, respectively,

Attached to the upper "face of the dia such upperface' being provided these con{ ductors being connected td posts 27 and 28 which in turn are connected by conductors 29 and 30 to the binding posts 31 and 32 carried by the'c'losure member 3 transmitter and receiver, not shown, the

conductors 33, 34 and the secondary coil 34: of the induction coil I being connected in circuit with the electromagnets 9 of the differential relay M. The conductors 35 and 3Glead from the relay member M, and are connected to the battery 38and the primary coil 37 of the induction coil 1 and the sec ondary coil 38 being in the line'between' the conductors 39 and coils 9 of the relay M. Thus it will be seen that the coils 9 of the relay relay the transmission from the circuit-including the conductors 33 and 34 to the circuit including the conductors 39 and 40 while the coils 9 of the relay M'- relay the transmission through the conductors 41, the primary coil 42 of the induction coil 1, the conductor. .43 and the battery 44.: to the transmission line includingthe conductors" 33 and 34c. By this arrangement it will be Seen that the proper voice or speech transmission may be had in both directions, as the circuit including the conductors 33 and 34. is properly equipped with a transmission apparatus, as wellas a receiving apparatus, while the circuit includingthe conductors 39 and L0 is similarly equipped.

When the present microphone is employed in' connection with a transmitter, the same is preferably constructed andarranged as shown inFigs. 8,9 and 10, the usual metal casing 45 belng provided withv the supporting apertured portion 46 and with the outstanding rim 47, the metal diaphragm .48 provided with the resilient supporting rim 49 being held in place by means of the usual spring clips 50.

A strip 51 which is provided with the bridging member 52 is connected diametrically to the rim l7 and socketed assat 52 for the adjustable reception of the stem 53, which is held in place by means of the screw 53. The receptacle 54 is carried upon the inner end of, the stem and is lined at opposite sides with the carbon strips 55, between which are disposed the conducting granules- 56 preferably of carbon. The casing 54 is opened at the end adj acent to the diaphragm 48 being sealed by the micadiaphragm 58 carrying the two non-conducting blades 23 which are similar to the blades 23 and are disposed to bepr'ojected within the granular particles 56 to agitate and compress the same. The diaphragm 58 is held seated upon the casing 54 by means of the closure or fastening member 59, while the pin 60 connects the diaphragm 48 to the diaphragm 58 so that when the diaphragm 48 is vibrated due to the effect of sound waves thereupon, the most sensitive vibrations are efiectual upon theparticles 56,it having been found with a micrpphone constructed according to the present invention, that the slightest variation in sound is transmitted and effected in the major circuit so that the finest articulation is possible;

i From the foregoing description, it is evident that with the agitators or compression members 23 and 23' disposed and arranged to coact with the particles, as shown'in the two forms of microphones here illustrated, the particles are not packed and rendered more conductive as is the case where plungers or buttons are used, butthat the strips 23 or 23' operating within the particles produce the most sensitive and minutest compression thereof, as well as the agitation thereof, so

that the slightest variation in the sound is The microphone as shown in Fig. 8 may be electrically connected to the transmitting line in any desired manner, the receptacle for holding the carbon particles eing an insulated member and having disposed therein, the necessary electrically conducting members-s0 that the carbon forms the transmitting means therebetween.

It will be noted that the strips 23 when used with a differential microphone, as shown in Figs. land 2, are so disposed as to be .in line with the poles 8 of the bi-polar receiver, and therefore to be positionedto be more greatly effected thereby solzhat the minutestvariations from the flow of" our blades disposed in paralle and actuated by the vibrating member, said blades being projected into the granular conducting material.v i m f I 2.,A microphone, havin a' support, a vibrating member 'mounte thereim -a receptacle of non-conducting material having and agitating .rent through the coils 9 will afiect vibra- ,lining two metal plates two of'the opposite walls of the chamber, granular conducting material in the chamber and bridging the two metal plates, and a compressing and a itatin blade actuated bythe vibrating mem eran disposed edgewise of and longitudinally within the chamber of the receptacle, said blade being in contact with the granular conducting material. 3. A microphone, including a support, a vibrating member, a .receptacle of non-conducting material adjustably mounted in the support relatively to the vibrating member and provided with a rectangular chamber, two metal plates abutting opposite walls of the chamber, granular conducting material mounted in the chamber and bridging the metal plates, and a plurality of compressing and agitating blades disposed in parallel a rectangular chamber,

and actuated by the vibrating member, said blades being projected within the receptacle into the granular conducting material.

'4. A microphone, including a support, a vibrating member, a receptacle composed of non-conducting material adjustably mounted in the support, the receptacle being provided with two chambers, granular conducting material mounted in each chamber, and two blades actuated by the vibrating member and projected one within each chamber.

In testimony that I claim the foregoing as my own I have hereto alfixed my signature in the presence of two witnesses.

CHARLES W. UNDERWOOD.

Witnesses:

SELINA WmLsoN, I. E. Smrson. 

